The present invention relates to an improved mesh and a printing screen for screen printing prepared with the mesh as well as a method for the preparation thereof. More particularly, the invention relates to a mesh for the preparation of a printing screen for screen printing having improved adhesion between the mesh and the photosensitive resin layer along with remarkably improved durability in screen printing therewith as well as a method for the preparation thereof.
As is known, the process of screen printing is performed by use of a printing screen prepared by providing a photosensitive resinous layer on a fine mesh made of filaments, of which the photosensitive layer is patterned by the photolithographic techniques. The meshes for such a printing screen were traditionally made of silk or very fine stainless steel wires. These traditional materials have several disadvantages. For example, silk-made meshes are defective in respect of the strength and dimensional stability while stainless steel-made meshes are not satisfactory in respect of elastic recovery and instantaneous repulsiveness if not to mention the expensiveness of both of these materials. In this regard, these traditional materials are being replaced more and more with filaments of polyester or nylon or, in particular, polyester utilizing their high dimensional stability. The meshes made of the filaments of these synthetic resins are of course not free from some problems including the poor receptivity of the photosensitive emulsion to form a photosensitive resinous layer on the mesh so that a uniform and sufficiently thick photosensitive layer can be formed only by repeating the coating works requiring handicraft-like skillfulness of the workers. Moreover, the adhesion of the thus formed photosensitive resinous layer to the surface of the mesh is low and poorly resistant against organic solvents used in the course of the printing works with the screen so that the durability of the printing screen is usually unsatisfactory.
Various attempts and proposals have been made in the prior art to solve the above described problems in the polyester or nylon-made mesh or printing screen made thereof including a chemical treatment of the mesh with an acid or alkali and physical treatment of the mesh with flame of corona discharge although no practically satisfactory results have yet been obtained rather with a disadvantage of decrease in the mechanical strength of the mesh.